Feeds

The secrets of spacetime revealed - on your workbench!

Boffin cooks up maker-style ‘quantum foam’ test kit

Next gen security for virtualised datacentres

Laser source? Check. Lenses? Check. A suspended block of glass? Check. A single-photon detector? Check. Supercooling apparatus? Check. Congratulations: put that kit together, and you might be able to help resolve some of the most fundamental questions of quantum physics.

OK, it might not be within reach of the backyard scientist, but the fascinating idea proposed in this Arxiv paper is that structures at the very smallest scale might be probed with a tabletop apparatus.

Let’s start by describing the problem: at the very finest scales, quantum mechanics predicts that what looks like a “smooth” universe of spacetime isn’t. In 1955, American theoretical physicist John Wheeler noted that long-established principles of quantum mechanics (like Heisenberg’s uncertainty principle) meant that at Planck scales, spacetime itself inherited the uncertainty of the quantum world. He coined the term “quantum foam” to describe this.

The problem is that while the “foamy” nature of quantum spacetime is predicted in the theory, it’s hard to test. As the paper notes, “detection of non-smooth spacetime texture at around the Planck scale is unfeasible with an elementary particle as probe. If we tried to localize the particle to the required scale, the uncertainty principle would require that we give the particle … energy of at least 1019 GeV; this is many orders of magnitude beyond what foreseeable particle accelerators can supply.”

The paper, by Jacob D. Bekenstein of the Racah Institute of Physics, Hebrew University of Jerusalem, proposes a startling workaround using the energies accessible to a tabletop research laser.

Berkenstein's quantum foam bench test

A simple view of Berkenstein's experiment: the photon emitter (right), lenses, and the glass block.

Source: http://arxiv.org/abs/1211.3816

Here’s the idea: fire a single photon at a dielectric block, and see whether the photon traverses the block or not. Photons interact poorly with matter – but they do interact. If the photon moves the block by more than the Planck distance (1.616199 × 10-35 meters), it will pass through. If the photon can’t move the block that distance, it won’t pass through, and the detector won't see it.

To take into account other uncertainties I won’t try to describe in full, Berkenstein proposes using classical mechanics to predict the number of photons that would be passed or reflected by the block on multiple runs. If the statistics gathered in the experiment differ from the classical prediction, he says, spacetime must be “lumpy” at the scale the experiment measures.

Bear with me, we’re nearly there: the final issue is how to “tweak” the scale at which the experiment might test spacetime for “quantum foam”. That’s relatively simple: use blocks of varying size, because they will absorb a different amount of momentum from the fired photons.

The blocks themselves have to be cooled close to absolute zero to minimise thermal noise in the experiment. ®

Bootnote: As an aside, the experiment takes advantage of yet another bit of quantum strangeness. It proposes using a single photon – but the lenses I mentioned at the top are designed to focus the light wave so that it’s the same size as the block. Wave-particle duality in practice! ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
Our LOHAN spaceplane ballocket Kickstarter climbs through £8000
Through 25 per cent but more is needed: Get your UNIQUE rewards!
LOHAN tunes into ultra long range radio
And verily, Vultures shall speak status unto distant receivers
NASA to reformat Opportunity rover's memory from 125 million miles away
Interplanetary admins will back up data and get to work
EOS, Lockheed to track space junk from Oz
WA facility gets laser-eyes out of the fog
Volcanic eruption in Iceland triggers CODE RED aviation warning
Lava-spitting Bárðarbunga prompts action from Met Office
LOHAN Kickstarter breaks NINETEEN THOUSAND of your EARTH POUNDS
That's right, OVER 9,000 beer tokens - and counting
Major cyber attack hits Norwegian oil industry
Statoil, the gas giant behind the Scandie social miracle, targeted
prev story

Whitepapers

Endpoint data privacy in the cloud is easier than you think
Innovations in encryption and storage resolve issues of data privacy and key requirements for companies to look for in a solution.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Advanced data protection for your virtualized environments
Find a natural fit for optimizing protection for the often resource-constrained data protection process found in virtual environments.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Next gen security for virtualised datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.